An inpatient program with selected overnight stays, for childhood and adolescent neuropsychiatric disorders has been initiated. Conditions currently under study are hyperactivity and Gilles de la Tourette syndrome. Pharmacological compounds under study in these disorders include methylphenidate, amphetamine, piribedil, and haldol. Pharmacokinetic studies with behavioral correlations are on-going. Central neurotransmitters and nucleotides and/or their metabolites are being studied in serum and urine. Early unpublished findings indicate that amphetamine is efficacious behaviorally only near its peak blood levels in a given child and its half-life is comparable to that of adults (approximately 18 hours). Behavior and motor activity correlate negatively with serum amphetamine levels within the first 4 hours of an initial dose.